- Apparent magnitude (Wikipedia)
Apparent magnitude (m) is a measure of the brightness of a star or other astronomical object. An object’s apparent magnitude depends on its intrinsic luminosity, its distance, and any extinction of the object’s light caused by interstellar dust along the line of sight to the observer.
- North Sea (Wikipedia)
The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium and France. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Sea in the north. It is more than 970 kilometres (600 mi) long and 580 kilometres (360 mi) wide, covering 570,000 square kilometres (220,000 sq mi).